Left 4 Dead 2

First: Welcome to one of the best co-op games of the past generation of gaming

second: don't expect friendly treatment from veterans, most L4D players want to play to win, the gameplay style of the game doesn't allow for teaching the ropes step by step, to avoid rude comments and getting constantly kicked I recommend you this:

Play singleplayer on beginner: The best way to learn the ropes of the game is playing by yourself

Learn the maps, routes, learn the music cues for every special infected, also learn the cues for when a horde is coming and learn the right spots to camp while facing a horde

Get the hang on how the special infected work and their attack patterns, if you want to play versus you will have to learn all this if you want to lead your team to win

Play with friends that have experience at this: The only people with enough patience to teach you the ropes are your friends, if you know someone who plays the game, then ask them to play with you so you learn what I mentioned above

Now... If you get kicked, remember, don't get upset, veterans aren't jerks, they are simply saving you from having an unpleasant time

I have no idea if veterans are jerks. I've played L4D2 a lot recently (since it was free, thank you Valve) and I've encountered nobody who's been rude towards me. Nobody. And I have NEVER been kicked. So I think you might be wrong about that.